The invention relates to a method for detecting a preinjection in an internal combustion engine with a common-rail system, including individual accumulators.
In an internal combustion engine, the quality of combustion and the composition of the exhaust gas are critically determined by the start of injection and the end of injection. In order to stay within legally prescribed limits, these two characteristics are usually automatically controlled by an electronic engine control unit. Another measure consists in preinjection, which reduces the rate of pressure rise in the cylinder and thus the mechanical loading of the components.
DE 103 44 181 A1 discloses a control method for an internal combustion engine with a common-rail system, including individual accumulators, in which the individual accumulator pressure distribution is detected and used to determine an injection end. On the basis of the injection end, a virtual injection start is then computed by a mathematical function. The virtual injection start is then set as the actual injection start for the continuing operation of the internal combustion engine. The cited document provides no information about a preinjection.